If you were to measure octopus smarts by the number of neurons the creatures have (500 million to our almost 100 billion), they’d come up pretty dull. But forget that metric. The octopus’s neurons aren’t even concentrated in its head; about two-thirds of its “brains” are distributed in its arms, dedicated to the fine operation of these limbs and each of their hundreds of suckers. The rest of the neurons are split between a central brain—surrounding the esophagus—and large optic lobes behind the eyes. Like we said: alien.
The octopus is weird: eerily malleable body, sucker-studded arms, skin that can transform into a convincing facsimile of seaweed—or sand—in a flash. It can solve mazes, open jars, use tools. It even has what seems to be a sophisticated inner life. What’s confusing about all this is that the octopus has a brain unlike that of almost any creature we might think of as intelligent. In fact, the octopus brain is so different from ours—from most of the animals we’re accustomed to studying—that it holds a rare promise: If we can figure out how the octopus manages its complex feats of cognition, we might be closer to discovering some of the fundamental elements of thought—and to developing new ideas about how mental capacity evolved. “Part of the problem in working out what’s essential to intelligence in the brain is working out which are the features that, if you took them away, you would no longer have an intelligent system,” says Peter Godfrey-Smith, a philosopher at CUNY who studies animal minds. “What’s essential as opposed to an accident of history?” Think about it: Chimpanzees are, like us humans, primates. Dolphins are mammals. Even clever crows and ravens are at least vertebrates. But our last common ancestor with the octopus was probably some kind of wormlike creature with eye spots that lived as many as 750 million years ago; the octopus has a sophisticated intelligence that emerged from an almost entirely different genetic foundation. If you want to study an alien intelligence, Godfrey-Smith says, “octopuses are the closest thing we have.”